[3.9] bpo-47104: Rewrite asyncio.to_thread tests to use IsolatedAsyncioTestCase (GH-32086)

Lib/test/test_asyncio/test_threads.py

@@ -5,87 +5,58 @@
 
 from contextvars import ContextVar
 from unittest import mock
-from test.test_asyncio import utils as test_utils
 
 
 def tearDownModule():
     asyncio.set_event_loop_policy(None)
 
 
-class ToThreadTests(test_utils.TestCase):
-    def setUp(self):
-        super().setUp()
-        self.loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(self.loop)
-
-    def tearDown(self):
-        self.loop.run_until_complete(
-            self.loop.shutdown_default_executor())
-        self.loop.close()
-        asyncio.set_event_loop(None)
-        self.loop = None
-        super().tearDown()
-
-    def test_to_thread(self):
-        async def main():
-            return await asyncio.to_thread(sum, [40, 2])
-
-        result = self.loop.run_until_complete(main())
+class ToThreadTests(unittest.IsolatedAsyncioTestCase):
+    async def test_to_thread(self):
+        result = await asyncio.to_thread(sum, [40, 2])
         self.assertEqual(result, 42)
 
-    def test_to_thread_exception(self):
+    async def test_to_thread_exception(self):
         def raise_runtime():
             raise RuntimeError("test")
 
-        async def main():
-            await asyncio.to_thread(raise_runtime)
-
         with self.assertRaisesRegex(RuntimeError, "test"):
-            self.loop.run_until_complete(main())
+            await asyncio.to_thread(raise_runtime)
 
-    def test_to_thread_once(self):
+    async def test_to_thread_once(self):
         func = mock.Mock()
 
-        async def main():
-            await asyncio.to_thread(func)
-
-        self.loop.run_until_complete(main())
+        await asyncio.to_thread(func)
         func.assert_called_once()
 
-    def test_to_thread_concurrent(self):
+    async def test_to_thread_concurrent(self):
         func = mock.Mock()
 
-        async def main():
-            futs = []
-            for _ in range(10):
-                fut = asyncio.to_thread(func)
-                futs.append(fut)
-            await asyncio.gather(*futs)
+        futs = []
+        for _ in range(10):
+            fut = asyncio.to_thread(func)
+            futs.append(fut)
+        await asyncio.gather(*futs)
 
-        self.loop.run_until_complete(main())
         self.assertEqual(func.call_count, 10)
 
-    def test_to_thread_args_kwargs(self):
+    async def test_to_thread_args_kwargs(self):
         # Unlike run_in_executor(), to_thread() should directly accept kwargs.
         func = mock.Mock()
 
-        async def main():
-            await asyncio.to_thread(func, 'test', something=True)
+        await asyncio.to_thread(func, 'test', something=True)
 
-        self.loop.run_until_complete(main())
         func.assert_called_once_with('test', something=True)
 
-    def test_to_thread_contextvars(self):
+    async def test_to_thread_contextvars(self):
         test_ctx = ContextVar('test_ctx')
 
         def get_ctx():
             return test_ctx.get()
 
-        async def main():
-            test_ctx.set('parrot')
-            return await asyncio.to_thread(get_ctx)
+        test_ctx.set('parrot')
+        result = await asyncio.to_thread(get_ctx)
 
-        result = self.loop.run_until_complete(main())
         self.assertEqual(result, 'parrot')
 
 

Misc/NEWS.d/next/Tests/2022-03-23-22-45-51.bpo-47104._esUq8.rst

@@ -0,0 +1,2 @@
+Rewrite :func:`asyncio.to_thread` tests to use
+:class:`unittest.IsolatedAsyncioTestCase`.